i'm bill hemmer in for shepard smith. welcome to studio b. break developments now in the terrorist attack. boston police, 30 minutes ago denying earlier reports that they have made an arrest. you can still see a large crowd outside the courthouse after early reports suggested that somebody was in custody. that's about a mile from our location, a mile east of where we are in boston's back bay. sources telling fox news -- and this is critical -- security video shows a, quote, young man carrying perhaps -- and perhaps dropping a black bag near the site of the second blast, a bag that may have caped a deadly bomb. we do not yet know if he is a suspect. we do not yet know if they've identified this person. today we saw crews coming through that site, combing through the site at 755 boylston street a quarter mile behind us here. rick leventhal with me now in boston. let me repeat the tweet that boston police sent out 30 minutes ago. despite reports to the contrary, there has not been arrest in the marathon attack. we're going to work through all th